The full function test kit will only test residual equipment ground-fault protection. Breakers configured for Modified Differential Ground Fault (MDGF) and Ground Source Return cannot be secondary-injection tested. The solution is to rack breaker out of cradle/cell to isolate from the MDGF system. If it is a fixed breaker, then remove MDGF wiring from terminals M1, M2 and M3 while using the FFTK (Full Function Test Kit).